Bolt anchor



Patented Nov. l5, 1927.

UNITED STATES Ltalu PATENT OFFlClE.

JOSEPH K. FISHER, OF SANTA MONICA, CALIFORNIA, ASSIGNOR TO TOEN EIWARZDOGDEN, OF MOUNTAINVILLE, NEW' YORK.

BOLT ANCHOR.

Application filed January 7, 1921.

My invention relates to improvements in bolt anchors or expansionshields, and has for its object the provision of a simplified and veryeffective device of this character.

In bolt anchors as heretofore made, it is customary to provide the bodyor walls of the anchor with external projections of one kind or another,which are forced against or into the surrounding material in which theanchor is placed as the latter is expanded, usually by a lag screw. Itis found that in this form of anchor the main body portion or walls ofthe anchor are more or less spaced from the surrounding material, thedegree of spacing depending among other things, upon the depth ofpenetration of the projections. In cases where the walls are in contactwith the surrounding material, the closeness or pressure of Contact onthe walls is not as great as would be the case if there were no externalprojections. It is also found that the external projections tend to cutgrooves in the surrounding material if for any reason the anchor isaccidently moved around or pulled out of the hole in which it is placed.

This grooving is objectionable for various reasons, among which thefollowing may be mentioned: When the anchor is reinserted in its hole,the projections will enter the grooves already formed, thus makingsatisfactory holding engagement well nigh impossible, or if suchengagement should be effected temporarily, there is the ever presentpossibility that it will be accidentally drawn out or rotated about itsaxis along the broken surface existing in the surrounding material.Furthermore, since the projections enter the surrounding mate-rial, thediameter of the hole is enlarged at those points with the result thateventually the hole would be too large for the anchor.

When soft metal sleeves with cylindrical outer surfaces are used, thesmoothness of their outer surfaces is more or less liable to slip andthus fail to provide the firm holding engagement with the surroundingmaterial which is needed.

It is the purpose of my invention to provide a bolt anchor which shallnot be open to the objections mentioned and which at the same time shallenable thorough gripping action to be obtained and which can bemanufactured at a minimum cost.

Briefly stated, the invention consists in providing the walls of theanchor with pits Serial No. 435,619.

or surface depressions instead of outwardly extending projections. Thesepits provide spaces into which the surrounding material may enter as theanchor is expanded into intimate contact therewith, the intrudedmaterial offering positive resistance to the with drawal or rotation ofthe anchor as long as the same is maintained in the expanded position.On the other hand, when the expanding means is removed, the anchor maybe readily withdrawn without any injury to the surrounding material andmay be replaced without any thought or care being given to the formerpositions occupied' by said depressions with respect to the surroundingmaterial. My invention also makes possible the obtainment of intimatecontact between the walls of the anchor and the surrounding material,thus materially increasing the frictional resistance obtained when `theanchor is expanded into place.

For a further understanding of the invention, reference is made to thedetail description and drawings forming a part of this specification.

In the drawings:

Figure l is a view showing an anchor which embodies this inventionhaving in its walls a series of pits in the form of perforations,portions being broken away to show the screw threads.

Figure 2 is a transverse section of the anchor shown in Figure l.

Figure 3 is a transverse section which shows the pits in the form ofsurface indentations or recesses.

Figure 4f is a transverse section which shows a shield provided withboth the pits and the surface indentations of Figures 2 and 3.

Figure 5 shows the invention applied to an anchor of the machine bolttype.

Figure 6 is a transverse section through the anchor body shown in Figure5.

In the drawings, like reference characters designate like partsthroughout the several views.

In the form ofthe invention shown in Figure l, the anchor consists of acylindrical body which is divided into at least two parts l0 and ll. Thebore of the anchor may be of any desirable or suitable shape and may beprovided with threads l2 for cooperation with the threads of a. lagscrew. At regular or irregular intervals the exterior walls of theanchor are provided with pits or recesses 13 of appreciable depth, thosein Figure 1 bein r shown as extending through the anchor waIls. In someinstances, it may not be desirable to perforate the walls of the anchorand in such cases shallow pits 13 may be provided, as shown in Figure 3.If desired, the depressions may consist of both recesses andperforations, as shown in Figure 4.

The invention is not limited to the form of anchor shown in Figure 1. Itmay be embodied in anchors which are adapted to be expandedby anysuitable means. As an example, I have shown in Figure 5, the inventionembodied in an anchor of the type adapted to be expanded by a machinescrew, a form well known in the art and comprising as usual separateparts 10 and 11 which together form at their ends inwardly tapered boresin which are fitted tapered expanding members 20, 21, one of which is acollar with a clearance hole for a bolt and the other of which isintcriorly threaded to form a nut.

wWhile I have illustrated the surface recesses or depressions as beingof diamondshaped form, it is to be distinctly understood that theinvention is notlimited to any particular form of pits or depressions.It is however, advantageous to have the edges of the pits or depressionswith well defined marginal edges.

What I claim is:

An expansion shield formed of relatively thick cast metal and having itsexterior expansible surface in the forni of a cylinder and surfacedepressions in said surface, said depressions being spacedcircumferentially and longitudinally and the marginal edges of thedepressions being well defined.

In witness whereof, I hereunto set my hand this 27 th day of December,1920.

JOSEPH K. FISHER.

